Substantial difficulty has heretofore been encountered in providing a down hole connector assembly that prevents well fluids from permeating the connector and electrical cable assembly. Fluid entering the connector can cause electrical faults in the connector itself, and can also escape through permeable portions of the electrical cable assembly into low pressure hazardous areas such as electrical enclosures within the well, above ground areas near the wellhead barrier, and even to the power transformer. Explosions or fires may occur in hazardous areas due to gases and other substances associated with the production of petroleum products being ignited by electric arcs. This endangers personnel and the general public by creating risk of electrical shock or death by electrocution in or near the hazardous area.
So far as known to applicant, the current art has failed to overcome the above and other problems. A substantial need therefore exists to provide a satisfactory and safe method and apparatus for supplying electrical power from an above ground power source, through hazardous areas, and into a well where down hole electrical connections are made.
Present commonly employed electrical installations typically comprise a flexible corrugated housing with an internal electrical conductor means, such as an insulated conductive wire, that extends from the above ground power source through the wellhead barrier and into the well. It is substantially difficult, if not impossible, to initiate and/or maintain an effective seal where the corrugated cable passes through the wellhead barrier to prevent fluid discharge from the well. It is also substantially difficult to seal the internal elements of a down hole connector and electrical cable from being permeated by well fluids.
The above mentioned problems worsen when pressure changes occur in the well. Although pressure changes caused by the formation can by regulated to some extent by the electrical submersible pump (“ESP”), when the ESP is turned off, the well can reach pressures at the wellhead in excess of 5,000 to 10,000 pounds per square inch. The high pressure forces well fluids to penetrate seams or gaps in the connector and saturate permeable materials, such as the rubber boot of the connector and conductive wire insulation. Once the insulation is permeated, the fluid can flow through the electrical cable and out into hazardous areas creating a potentially explosive situation.
Currently known electrical installations have attempted to overcome the above mentioned problems by providing a connector made with an external protective sleeve that protects the internal rubber boots of the connector and prevents their outward expansion. The protective sleeve itself is typically comprised of two mating parts that allow the connection to be disconnected. However, even if the two parts of the shield are fastened or otherwise locked together, as is typical, the pressure differentials in the well often cause a piston effect between the rubber boots that forces the electrical connection apart. It is therefore desirable to provide a connector capable of remaining intact during pressurization and depressurization within the well.
Other electrical installations, such as those described in U.S. Pat. No. 4,614,392, Boyd B. Moore (the “'392 patent”), have attempted to solve the above mentioned problems with connectors positioned next to or inside of the encapsulated pressurized areas of the well. The '392 patent, for example, discloses how to seal electrical conductor wires that pass through a packer inside of steel tubes in order to provide conduction from a low pressure area above the packer to a high pressure area below the packer. In the '392, on either side of the packer, the steel tubes terminate using a known coupling assembly and insulator stand off provides the means to electrically isolate the crimp sleeve/connector socket joining the two conductor wires. It has been discovered, however, that in certain applications well fluids may penetrate the insulator stand off surrounding the connector socket and reach the conductive wire. Such fluid penetration causes the fluid to slowly escape to the low pressure area and into contact with the conductors. It is desired, therefore, to provide a more effective fluid seal, so that connectors placed in or near down hole pressurized areas will not leak fluids to low pressure areas.
Other commonly employed electrical installations have attempted to solve the above mentioned problems while, at the same time, providing a connecter than can be disconnected if the well, down hole equipment, electrical assembly, or other interconnected structures need to be removed. These installations typically comprise a connecter made with an attachment plug and a receptacle. The plug and receptacle design selectively connect and disconnect to terminate the above ground power source to down hole equipment. Under applicable regulations and/or industry standards the attachment plug and receptacle should have the same power rating as the device to which power is being supplied. However, so far as known to applicant, the attachment plug and receptacle connectors do not have such a rating and are incapable of withstanding an internal explosion without risk to the operator and drilling operations.
Another problem with the attachment plug and receptacle is that it frequently fails to stay connected when the well is suddenly pressurized or depressurized. During pressurization the connector's internal rubber boots often become impregnated with fluid and expand, which may force apart the connector's mating counterparts. During depressurization, fluid impregnated rubber boots may fail to release the fluids fast enough resulting a disconnect. It is therefore desirable to provide a down hole connector that can selectively terminate the above ground power source with down hole equipment that is not adversely affected by well pressures. Alternatively, it is desirable to provide a connector or an electrical cable connection assembly that can be efficiently and inexpensively cut off and replaced by a new connector or electrical cable connection assembly without substantial expense to the operator or delay in well operations.